It is common practice to tow trailers, recreational vehicles and the like behind and utilizing automobiles and trucks. For relatively small and lightweight towed vehicles or trailers, conventional Class 1, Class 2 and Class 3 ball-type hitches are commonly mounted to vehicle bumpers and frames. However, as the size and weight of the trailer increases, it is essential that the loads imposed on the vehicle by the trailer be adequately secured and distributed.
Typical of the problem presented is the towing of a large and heavy trailer behind a conventional pickup truck. In these applications, in place of a ball hitch, it is known to use a “fifth wheel” trailer hitch assembly, similar, in many respects, to the fifth wheel hitch coupling used by large highway cargo-hauling tractor/trailers. By using a fifth wheel type trailer hitch mounted directly over or ahead of the rear axle of a pickup truck, such a vehicle can adequately accommodate large and heavy trailers.
It is well known, therefore, to install fifth wheel-type hitches in the beds of pickup trucks, so that the trailer tongue (or “gooseneck”) is secured to the towing vehicle bed at the proper longitudinal axes of the vehicle to optimize the placement of the loads imposed by the trailer. Additionally, forward placement of the tongue of the towed trailer in relation to the towing vehicle's wheelbase improves the towing characteristics of the trailer, helping to minimize undesirable sway and oscillation.
Numerous techniques for securing the fifth wheel to the truck bed have been disclosed. See, for example, U.S. Pat. No. 6,158,761, to King and U.S. Pat. No. 6,557,883 to Linger, et al. Typical systems involve the placement of reinforcing mounting rails on the upper surface of the pickup truck bed, and providing such mounting rails with receptacles which will engage corresponding lugs on the fifth wheel assembly. This configuration is desirable so that the fifth wheel assembly can be readily removed from the towing vehicle, to open the cargo area of the towing vehicle for load carrying and tasks. Numerous similar methodologies have been used in the past, all designed to achieve the same goals, i.e., removability so that the vehicle can be used as a cargo-carrying vehicle, and sturdiness, so that when used as a towing vehicle, the appropriate support is provided by the towing vehicle's bed and mounting rails.
While these prior art systems have worked adequately, it has long been recognized that the presence of permanently mounted support rails in the bed of the pickup truck is still undesirable, in that these mounting rails present some obstacle to the loading and unloading of the bed of the vehicle. Recognizing this limitation, at least one motor vehicle manufacturer has designed and incorporated into its pickup truck a recessed mounting system. Such a system is disclosed in U.S. Pat. No. 7,121,573 to Lindeman, et al. This system moves the supports for the fifth wheel assembly to the underside of the truck bed, and provides the supports with recessed receptacles or sockets which are substantially flush with the truck bed upper surface. In this fashion, the truck bed remains relatively unobstructed when the fifth wheel assembly is not installed.
Fifth wheel trailer hitch assemblies are, not unexpectedly, expensive because of their mechanical complexity as well as the requirement that they be extremely sturdy. The newer fifth wheel mounting scheme taught by Linderman suffers from the requirement that a specialized fifth wheel hitch assembly be utilized, so that the fifth wheel assembly-mounting scheme is complimentary with the array of mounting sockets installed in the truck bed. For obvious reasons, owners of older fifth wheel assemblies would prefer not to have to incur the expense of buying an entire new assembly, and discarding an older style.
A need exists, therefore, for adapting older style fifth wheel trailer hitches to newer style truck bed mounting arrays. The present invention addresses this need.